Slider with underpass leads and methods of fabrication

ABSTRACT

A slider is disclosed having a continuous coil including front coils, back coils, and a center tab, a write head including upper and lower poles which sandwich at least a portion of the front coils of the continuous coil, and at least one underpass lead, which passes under a portion of the back coils of the continuous coil to make electrical connection with the center tab of the continuous coil. Also disclosed are first and second variations of methods for fabricating the slider with underpass leads.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to computer disk drives and morespecifically to fabrication of the induction coil for use with magneticwrite heads.

2. Description of the Prior Art

A computer disk drive stores and retrieves data by positioning amagnetic read/write head over a rotating magnetic data storage disk. Thehead, or heads, which are typically arranged in stacks, read from orwrite data to concentric data tracks defined on surface of the diskswhich are also typically arranged in stacks. The heads are included instructures called “sliders” onto which the read/write sensors of themagnetic head are fabricated. The slider flies above the surface of thedisks on a thin cushion of air, and the surface of the slider whichfaces the disks is called an Air Bearing Surface (ABS).

FIG. 3 shows a detail view of a magnetic head 14. A coil 18 is includedwhich is configured as a single long strip, which is then curved intothe coil shape. There is thus an inner-most turn of the coil, which willbe referred to, for convenience, as the coil center 34. There is also anouter-most end 36 to which electrical connection is made to pads (notshown). A center connection called the center tab 38 makes an electricalconnection to the coil center 34, thus allowing the coil to be energizedto create the magnetic field by which writing operations areaccomplished. To make electrical connection with the center tab 38, ithas been the common practice to create an overpass lead 40 which reachesover the coil 18 and makes this connection to the center tab 38.Although this has been the general practice in the slider fabricationindustry, this configuration has several disadvantages.

During fabrication, it is common to create a coil interconnect 39 (notvisible in FIG. 3) which refers to the pedestal or layer plated on thelocation of the coil center tab for the connection of the coil centertab to the overpass lead 40.

During perpendicular and single layer coil longitudinal write headproduction, the write pole can be formed by the ion milling process.Damage due to ion milling on the coil interconnect, and the tallre-deposition “fence” surrounding the interconnect edges can result.These tall “fences” present problematic areas for subsequent wetprocessing As a result, solutions from wet processing seeps throughareas around the “fences” and attack the expose coil interconnect,causing interconnect materials to be etched away. Prior solutions cannoteliminate this problem completely. In such a small area, such as thecentral tab, reducing the interconnect metal will lead to reducing thechance of a good contact between the “over passing” lead and the coilinterconnect. When poor contact to either the coils or other featuressuch as the electronic lapping guides (ELG) result, the head isscrapped. The longer the small electrical interconnects for the coil andlapping guides are exposed on the wafer, the greater the chance ofdamage or poor electrical contact resulting. Also, with the overpasslead design, electrical testing of the coil and ELG is not possibleuntil near the end of the manufacturing line. If a problem arises in thecoil or ELG processing, it can take up to a few weeks to detect, duringwhich further production is jeopardized.

One of the present inventors has previously addressed this problem bypatenting method and apparatus in U.S. Pat. No. 5,486,968 and U.S. Pat.No. 5,761,013 which include a planarization layer having three sections,two of which connect to MR leads and the third of which connects to theinner coil tab of the inductive coil. The overpass lead is thus replacedby planarization layer which passes under the coils. At the time ofthese earlier inventions, it was thought to be an important advantage ofthis planarization layer that it provide a flat surface to build thecoils upon. Earlier attempts to make an “underpass” lead left lumps inthe surface where the coils were to be deposited, which often impairedthe quality of coils. Thus the planarization layer was intended to covermost of the area on which the coil was to be deposited, and thus wasmore extensive than necessary for the purpose of providing an electricallead to the coil interconnect. Fabrication of an extensive element suchas the planarization layer naturally consumes more time and materialsthan fabrication of an underpass lead of smaller extent, when theunderpass lead is not used for the dual purpose of providing anelectrical path and also forming a flat platform for construction of theinduction coil.

Thus there is a need for a slider having an underpass lead which is notconstrained in shape to act as a planarization layer for induction coilfabrication. There is also a need for a simplified method of fabricationfor a slider having such an underpass lead.

SUMMARY OF THE INVENTION

A first embodiment of the present invention is a slider having acontinuous coil including front coils, back coils, and a center tab, awrite head including upper and lower poles which sandwich at least aportion of the front coils of the continuous coil, and at least oneunderpass lead, which passes under a portion of the back coils of thecontinuous coil to make electrical connection with the center tab of thecontinuous coil.

Also disclosed are first and second variations of methods forfabricating the slider with underpass leads.

It is an advantage of the present invention that fabrication of the coiland therefore of the entire magnetic head is simplified.

It is a further advantage that the lead to the center tab of the coilpasses under the coil, so that fabrication of the coil is simplified.

It is another advantage that the underpass lead can be made of almostany shape, and is not constrained to being a flat plane.

It is yet another advantage that after fabrication of the coil,interconnects are then buried before write pole processing, reducingtheir exposure to damage in subsequent processing.

It is a further advantage that the coils and ELGs can be electricallytested immediately after the coil fabrication process, as opposed tosignificantly later in the manufacturing line. Therefore, defects in thecoils may be detected at much earlier stages, leading to less scrap.

An additional advantage is that the area of the under passing lead canbe spread out to allow cooling of the coil through heat sinking effects.

These and other features and advantages of the present invention will nodoubt become apparent to those skilled in the art upon reading thefollowing detailed description which makes reference to the severalfigures of the drawing.

IN THE DRAWINGS

The following drawings are not made to scale as an actual device, andare provided for illustration of the invention described herein.

FIG. 1 shows a top plan view of an exemplary disk drive;

FIG. 2 illustrates a perspective view of view of an exemplary slider andsuspension;

FIG. 3 shows a top plan view of an exemplary read/write head;

FIG. 4 is a cross-section view of a perpendicular read/write head havingan overpass lead of the prior art;

FIG. 5 is a cross-section view of a longitudinal read/write head havingan overpass lead of the prior art;

FIG. 6 is a top plan view of a planarization layer of the prior art;

FIG. 7 is a top plan view of a planarization layer with coil of theprior art;

FIGS. 8-13 show cross-sectional views of stages in a first variation ofthe method of fabrication of a slider with underpass lead of the presentinvention;

FIG. 14 is a cross-sectional view of a perpendicular read/write headhaving an underpass lead fabricated according to the first variation ofthe method of fabrication of the present invention;

FIG. 15 is a cross-sectional view of a longitudinal read/write headhaving an underpass lead fabricated according to the first variation ofthe method of fabrication of the present invention;

FIGS. 16-21 show cross-sectional views of stages in a second variationof the method of fabrication of a slider with underpass lead of thepresent invention;

FIG. 22 is a cross-sectional view of a perpendicular read/write headhaving an underpass lead fabricated according to the second variation ofthe method of fabrication of the present invention;

FIG. 23 is a cross-sectional view of a longitudinal read/write headhaving an underpass lead fabricated according to the second variation ofthe method of fabrication of the present invention;

FIGS. 24-26 show top plan views of stages in the fabrication of a sliderhaving underpass leads of the present invention; and

FIG. 27 shows a top plan view of another variation in the shape of theunderpass leads of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

A magnetic disk drive 2 is shown generally in FIG. 1, having one or moremagnetic data storage disks 4, with data tracks 6 which are written andread by a data read/write device 8. The data read/write device 8includes an actuator arm 10, and a suspension 12 which supports one ormore magnetic heads 14 included in one or more sliders 16.

FIG. 2 shows a slider 16 in more detail being supported by suspension12. The magnetic head 14 is shown in dashed lines, and in more detail inFIGS. 3-7. The magnetic head 14 includes a coil 18 and P1 pole 20. Thesecond pole P2 22 is separated from P1/S2 by write gap 23. In aconfiguration of read head where Current is Perpendicular to the Plane(CPP), Shield S1 30 and P1/S2 20 act as electrodes supplying current tothe read sensor 50 which lies between them. An insulation layer 32 alsoseparates the S1 30 and P1/S2 20 electrodes in the area behind the readsensor 42, so that they do not short out along their length.

The magnetic head 14 flies on an air cushion between the surface of thedisk 4 and the air bearing surface (ABS) 24 of the slider 16. The writehead portion 26 and the read head portion 28 are generally shown, withthe read head sensor 50 and the ABS 24.

Returning to FIG. 3, the coil 18 is configured as a single long strip,which is then curved into the coil shape. There is thus an inner-mostend of the coil, which will be referred to for convenience as the coilcenter 34, as well as an outer-most end 36. A center connection calledthe center tab 38 makes an electrical connection to the coil center 34,thus allowing the coil to be energized to create the magnetic field bywhich writing operations are accomplished. During fabrication, it iscommon to create a coil interconnect 39 (not visible in FIG. 3) whichrefers to the pedestal or layer plated on the location of the coilcenter tab 38. To make electrical connection with the center tab 38, ithas been the common practice to create an overpass lead 40 which reachesover the coil 18 and makes this connection to the center tab 38.Although this has been the general practice in the slider fabricationindustry, this configuration has several disadvantages, as discussedabove, in terms of difficulty of processing and fabrication.

The present invention, as shown in FIGS. 14-15, 21-22, and 26-27 is aslider with underpass leads 50, which uses an “under passing” lead toconnect the bonding pads to the coil 18 at the coil interconnect 39, andthe electrical lapping guides (ELGs) at their interconnects. In thisdesign, the coil interconnect 39 is not exposed to the harsh millingfrom the write pole processing because no interconnect metal is exposedat the milling surface. Thus no interconnect metal etching or “fencing”occurs. Thus, there is no interaction with subsequent wet processing.

In addition to ensuring good contact between the lead and the coil, the“under passing” design has three additional benefits. First, the area ofthe “under passing’ lead can be spread out to allow cooling of the coilthrough heat sinking effects. Secondly, using the underpassing lead, thecoils and ELGs can be electrically tested immediately after the coilprocess, as opposed to significantly later in the manufacturing line.This will lead to earlier detection of problems in the coil and ELGprocesses, leading to less scrap. After the coil process, theseinterconnects are then buried before write pole processing, reducingtheir exposure to damage in subsequent processing.

Turning now to FIG. 6-7 (Prior art), one of the present inventors haspreviously addressed this problem by including a planarization layer 3having three sections 5, 7, 9, two of which, sections 7, 9 connect to MRleads (not shown) and the third of which, section 5 connects to theinner coil tab 38 of the inductive coil 18. The overpass lead is thusreplaced by planarization layer 3 which passes under the coils 18.

At the time of these earlier inventions, it was thought to be animportant advantage of this planarization layer that it provide a flatsurface to build the coils upon. Earlier attempts to make an “underpasslead” left lumps in the surface where the coils were to be deposited,which often impaired the quality of coils. Thus the planarization layerwas intended to cover most of the area on which the coil was to bedeposited, and thus was more extensive than necessary for the purpose ofmerely providing an electrical lead to the coil interconnect.

Advances in fabrication technology have now made it possible to useunderpass leads 58 (see FIGS. 14-15, 21-22, and 26-27) which are of mostany shape, and are not restricted to the planarization layer structureof the prior art. Thus underpass leads 58 can be of very minimal extentand can be placed to connect to the coil center tab 38 and then thewhole area treated with Chemical Mechanical Polishing (CMP) to produce aflat floor for construction of the induction coil 18. The underpass lead58 can also be shaped for other secondary purposes, such as to sink theheat from a certain portion of the coil 18 or heat a certain portion ofthe slider 50, without affecting the rest. The underpass lead 58 thusalso avoids the disadvantages of the overpass lead discussed above.

The important stages in a first variation of fabrication of a slider 50of the present invention having an underpass lead 58 are shown in FIGS.8-15. In a cross-sectional view, the turns of the induction coil 18 areshown as blocks. The blocks representing the cross-sections of the coilscan be thought of as having two sections or as forming two groups oneither side of the center tab or coil interconnect. One group of coilslies closer to the ABS 24 and these are enclosed by the write head firstand second poles 20, 22 (see FIG. 5). For ease of reference in thefigures that follow, this group will be referred to the front coil group54, and the other group lies on the side of the slider farthest from theABS, and will be referred to as the back coil group 56 (see FIGS. 13 and21). Since the turns represented by these blocks actually make up onecontinuous coil, the left most block of the front coil group 54continues out of the plane of the paper to become the right-most blockof the back coil group 56, which then goes on into the plane of thepaper to become the second left-most of the front coil group 54, and soon working towards the center of the coil, to terminate with the coilcenter 34 or center tab 38.

On the scale shown, the two groups are actually separated much fartherthan shown, thus wave brackets are shown to indicate that more distanceexists between the two sides which is not shown. Even so, no attempt hasbeen made to draw the elements to scale. Also, in the figures whichfollow, the terms front coil group site 55 and back coil group site 57will be used to indicate the sites where these groups will be eventuallylocated, even when the coil loops have not yet been fabricated on thesesites.

FIG. 8 shows the initial stage in the fabrication of the slider withunderpass lead 50. The S1 layer 30, read head transducer 33 and S2 layer31 have been fabricated according to conventional processing steps knownin the art on the front coil group site 55. An insulation layer 52 isthen deposited on the front coil group site 55 and the back coil groupsite 57. The insulation layer 52 on the back coil group site 57 covers aconventional substrate, not shown here.

FIG. 9 shows the addition of the underpass lead 58 upon the insulationlayer 52 at the back coil group site 57. As discussed above, thisunderpass lead 58 can be made in a number of shapes and configuration,and is not restricted to being a planarized surface as a platform forcoil formation.

FIG. 10 shows the formation of the P1 pole 20 of the write head 26 onthe front coil group site 55, and also the coil interconnect 39 isformed on the underpass lead 58 at the back coil group site 57. The P1pole 20 and coil interconnect 39 are preferably of the same material,which makes this stage more efficient, as they can be completed in asingle step, rather than in separate stages.

FIG. 11 shows the next stage in which fill material 60 is preferablyalumina but which could include SIO₂ or other non-doped, non-conductivedielectics is deposited in the openings 62 to the sides of the P1 pole20 and coil interconnect 39. Chemical Mechanical Polishing (CMP) is nextused to planarize the upper surface of the structure.

FIG. 12 shows insulation material 64 has been added, with gaps 66, 68left in the insulation material 64.

FIG. 13 shows the formation of the front coil group 54 and back coilgroup 56 of the coil 18, including the coil center 34, which also servesas the coil center tab 38 and thus forms electrical connection with theunderpass lead 58.

From this point, the fabrication is completed by conventional techniquesto fabricate the second pole P2 22 to make the perpendicular writinghead shown in FIG. 14, or the longitudinal writing head shown in FIG.15.

The important stages in a second variation of fabrication of a slider 50having an underpass lead 58 are shown in FIGS. 16-23.

FIG. 16 shows the initial stage in the fabrication of the alternateslider with underpass lead 70. The S1 layer 30, read head transducer 33and S2 layer 31 have been fabricated according to conventionalprocessing steps known in the art on the front coil group site 55. Acenter tab support 72 is deposited on the back coil group site 57 at thesame time as the S2 layer 31.

FIG. 17 shows the addition of an insulation layer 52 which covers the S1layer 31 and center tab support 72 on the front coil group site 55 andback coil group site 57 respectively.

FIG. 18 shows the plating of the P1 pole 20 as well as the underpasslead 58 which now includes an underpass strap 74 which follows thecontours of the step 76 created by the placement of the center tabsupport 72. The P1 pole 20, the underpass lead 58, and underpass strap74 are preferably of the same material, which makes this stage moreefficient, as they can be completed in a single operation, rather thanin separate stages. As before, this underpass lead 58 can be made in anumber of shapes and configuration, and is not restricted to being aplanarized surface as a platform for coil formation.

FIG. 19 shows the next stage in which fill material 60 is preferablyalumina, but which could include SIO₂ or other non-doped, non-conductivedielectics, is deposited in the gaps 62 to the sides of the P1 pole 20and underpass lead 58. Chemical Mechanical Polishing (CMP) is next usedto planarize the upper surface of the structure.

FIG. 20 shows insulation material 64 has been added, with openings 66,68 left in the insulation material 64.

FIG. 21 shows the formation of the front coil group 54 and back coilgroup 56 of the coil 18, including the coil center tab 38 and thus formselectrical connection with the underpass lead 58.

From this point, the fabrication is completed by conventional techniquesto fabricate the second pole P2 22 to make the perpendicular writinghead shown in FIG. 22, or the longitudinal writing head shown in FIG.23.

FIGS. 24-27 show some major stages of the fabrication process from anoverhead view. In FIG. 24, underpass layers 58 are shown to have beenfabricated, which include a first underpass lead 59 and a secondunderpass lead 61. In FIG. 25, lower pole layer 20 has been shown tohave been deposited onto the underpass layers 58, with the center tab 34in place on the second underpass lead 61. FIG. 26 shows the depositionof the coil 18, with the outer-most end 36 attached to the firstunderpass lead 59 and the center coil 34 connected to the center tab 38.

As discussed above the underpass leads are not restricted to being aplanarization layer, as in the prior art, and can take many shapes andconfigurations. FIG. 27 shows a variation in which the second underpasslead 61 has been configured to include a cooling plate 78, which may beuseful in conducting heat away from the coils 18. This is of course onlyone of many shapes that either of the underpass leads 58 may take. Thisfreedom of configuration constitutes a major difference between theunderpass leads of the present invention and the planarization layer ofthe prior art.

While the present invention has been shown and described with regard tocertain preferred embodiments, it is to be understood that modificationsin form and detail will no doubt be developed by those skilled in theart upon reviewing this disclosure. It is therefore intended that thefollowing claims cover all such alterations and modifications thatnevertheless include the true spirit and scope of the inventive featuresof the present invention.

1. A method of fabrication of a slider with underpass leads, said sliderhaving sites for fabrication of a continuous coil having a set of frontcoils and a set of back coils and a center tab, said method comprising:A) fabricating a first shield layer, a read head sensor, a second shieldlayer and a substrate layer to produce an upper surface which includessaid second shield layer on said site for front coils and a portion ofsaid substrate layer on said site for said back coils; B) depositing aninsulation layer upon said upper surface formed by said second shieldlayer which serves as a site for said front coils, also depositing saidinsulation layer on said portion of said substrate layer which serves asa site for said back coils; C) fabricating at least one underpass leadlayer upon said insulation layer covering said portion of said substratelayer which serves as a site for said back coils; D) fabricating a lowerwrite pole on said insulation layer covering said second shield layerwhich serves as a site for said front coils, also fabricating a coilinterconnect on said underpass lead layer; E) filling with fill materialand forming a flat top surface by CMP; F) depositing insulation materialon said flat top surface and forming a pole gap which reaches to aportion of said lower write pole and a center tab gap in said insulationmaterial which reach to a portion of said coil interconnect, theremaining insulating material on said lower write pole forming a sitefor front coils and the remaining insulating material on said at leastone underpass lead, forming a site for back coils; and G) fabricatingsaid continuous coil so that said front coils are formed on said sitefor front coils, said back coils are formed on said site for back coils,and said center tab is formed on said center tab gap.
 2. The method offabrication of claim 1, further comprising: H) fabrication of the secondpole to complete the write head.
 3. The method of fabrication of claim2, wherein: said write head is configured as a perpendicular write head.4. The method of fabrication of claim 2, wherein: said write head isconfigured as a longitudinal write head.
 5. The method of fabrication ofclaim 1, wherein: fabrication of the lower write pole and fabrication ofthe coil interconnect of D) are completed simultaneously.
 6. The methodof fabrication of claim 1, wherein: said fill material of E) is chosenfrom group consisting of alumina, SIO₂ and other non-doped,non-conductive dielectics.
 7. A method of fabrication of a slider withunderpass leads, said slider having sites for fabrication of acontinuous coil having a set of front coils and a set of back coils anda center tab, said method comprising: A) fabricating first shield layer,a read head sensor, and a second shield layer where said second shieldlayer forms said site for said front coils, and also fabricating acenter tab support on a substrate layer, where said center tab supportforms said site for said center tab, and a portion of said substratelayer forms said site for said back coils; B) depositing an insulationlayer upon said upper surface formed by said second shield layer whichserves as a site for said front coils, and also depositing an insulationlayer on said center tab support and said portion of said substratelayer which forms said site for said back coils; C) fabricating a lowerwrite pole on said insulation layer covering said second shield layerwhich serves as a site for said front coils, also fabricating at leastone underpass lead layer upon said insulation layer covering saidportion of said substrate layer which serves as a site for said centertab and said back coils, said underpass lead including an underpassstrap; D) filling with fill material and forming a flat top surface byCMP; E) depositing insulation material on said flat top surface andforming a pole gap which reaches to a portion of said lower write poleand a center tab gap in said insulation material which reach to aportion of said underpass lead, the remaining insulating material onsaid lower write pole forming a site for said front coils and theremaining insulating material on said at least one underpass leadforming a site for said back coils; and F) fabricating said continuouscoil so that said front coils are formed on said site for front coils,said back coils are formed on said site for back coils, and said centertab is formed on said center tab gap.
 8. The method of fabrication ofclaim 7, further comprising: G) fabrication of the second pole tocomplete the write head.
 9. The method of fabrication of claim 8,wherein: said write head is configured as a perpendicular write head.10. The method of fabrication of claim 8, wherein: said write head isconfigured as a longitudinal write head.
 11. The method of fabricationof claim 7, wherein: fabrication of the lower write pole and fabricationof at least one underpass lead layer of C) are completed simultaneously.12. The method of fabrication of claim 7, wherein: said fill material ofE) is chosen from group consisting of alumina, SIO₂ or other non-doped,non-conductive dielectics.
 13. A slider comprising: a continuous coilincluding front coils and back coils, and a center tab; a write headincluding upper and lower poles which sandwich at least a portion ofsaid front coils of said continuous coil; and at least one underpasslead, which passes under a portion of said back coils of said continuouscoil to make electrical connection with said center tab of saidcontinuous coil.
 14. The slider of claim 13, wherein: said write head isconfigured as a perpendicular write head.
 15. The slider of claim 13,wherein: said write head is configured as a longitudinal write head. 16.The slider of claim 13, wherein: said underpass lead is configured as acooling plate.
 17. The slider of claim 13, wherein: said underpass leadand said center tab are connected by a coil interconnect.
 18. A diskdrive comprising: at least one hard disk; at least one slider including:a continuous coil including front coils and back coils, and a centertab; a write head including upper and lower poles which sandwich atleast a portion of said front coils of said continuous coil; and atleast one underpass lead, which passes under at least a portion of saidcontinuous coil to make electrical connection with said center tab ofsaid continuous coil.
 19. The disk drive of claim 18, wherein: saidwrite head of said at least one slider is configured as a perpendicularwrite head.
 20. The disk drive of claim 18, wherein: said write head ofsaid at least one slider is configured as a longitudinal write head. 21.The disk drive of claim 18, wherein: said underpass lead is configuredas a cooling plate.
 22. The disk drive of claim 18, wherein: saidunderpass lead and said center tab are connected by a coil interconnect.